[DebugInfo] Insert DW_OP_deref when spilling indirect DBG_VALUEs

Summary: This comes up in optimized debug info for C++ programs that pass and return objects indirectly by address. In these programs, llvm.dbg.declare survives optimization, which causes us to emit indirect DBG_VALUE instructions. The fast register allocator knows to insert DW_OP_deref when spilling indirect DBG_VALUE instructions, but the LiveDebugVariables did not until this change. This fixes part of PR34513. I need to look into why this doesn't work at -O0 and I'll send follow up patches to handle that. Reviewers: aprantl, dblaikie, probinson Subscribers: qcolombet, hiraditya, llvm-commits Differential Revision: https://reviews.llvm.org/D37911 llvm-svn: 313400
2024-11-23 19:23:23 +01:00 · 2017-09-15 21:54:38 +00:00 · 2017-09-15 21:54:38 +00:00 · 4d55207ede
commit 4d55207ede
parent 8b03488b24
4 changed files with 248 additions and 38 deletions
--- a/lib/CodeGen/LiveDebugVariables.cpp
+++ b/lib/CodeGen/LiveDebugVariables.cpp
@ -108,8 +108,8 @@ class LDVImpl;
 /// held by the same virtual register. The equivalence class is the transitive
 /// closure of that relation.
 class UserValue {
-  const MDNode *Variable;   ///< The debug info variable we are part of.
-  const MDNode *Expression; ///< Any complex address expression.
+  const DILocalVariable *Variable; ///< The debug info variable we are part of.
+  const DIExpression *Expression; ///< Any complex address expression.
  bool IsIndirect;        ///< true if this is a register-indirect+offset value.
  DebugLoc dl;            ///< The debug location for the variable. This is
                          ///< used by dwarf writer to find lexical scope.
@ -132,8 +132,9 @@ class UserValue {
  void coalesceLocation(unsigned LocNo);

  /// insertDebugValue - Insert a DBG_VALUE into MBB at Idx for LocNo.
-  void insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx, unsigned LocNo,
-                        LiveIntervals &LIS, const TargetInstrInfo &TII);
+  void insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx,
+                        unsigned LocNo, bool Spilled, LiveIntervals &LIS,
+                        const TargetInstrInfo &TII);

  /// splitLocation - Replace OldLocNo ranges with NewRegs ranges where NewRegs
  /// is live. Returns true if any changes were made.
@ -142,8 +143,8 @@ class UserValue {

 public:
  /// UserValue - Create a new UserValue.
-  UserValue(const MDNode *var, const MDNode *expr, bool i, DebugLoc L,
-            LocMap::Allocator &alloc)
+  UserValue(const DILocalVariable *var, const DIExpression *expr, bool i,
+            DebugLoc L, LocMap::Allocator &alloc)
      : Variable(var), Expression(expr), IsIndirect(i), dl(std::move(L)),
        leader(this), locInts(alloc) {}

@ -159,8 +160,8 @@ public:
  UserValue *getNext() const { return next; }

  /// match - Does this UserValue match the parameters?
-  bool match(const MDNode *Var, const MDNode *Expr, const DILocation *IA,
-             bool indirect) const {
+  bool match(const DILocalVariable *Var, const DIExpression *Expr,
+             const DILocation *IA, bool indirect) const {
    return Var == Variable && Expr == Expression && dl->getInlinedAt() == IA &&
           indirect == IsIndirect;
  }
@ -262,12 +263,14 @@ public:
                     LiveIntervals &LIS);

  /// rewriteLocations - Rewrite virtual register locations according to the
-  /// provided virtual register map.
-  void rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI);
+  /// provided virtual register map. Record which locations were spilled.
+  void rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI,
+                        BitVector &SpilledLocations);

  /// emitDebugValues - Recreate DBG_VALUE instruction from data structures.
-  void emitDebugValues(VirtRegMap *VRM,
-                       LiveIntervals &LIS, const TargetInstrInfo &TRI);
+  void emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS,
+                       const TargetInstrInfo &TRI,
+                       const BitVector &SpilledLocations);

  /// getDebugLoc - Return DebugLoc of this UserValue.
  DebugLoc getDebugLoc() { return dl;}
@ -297,11 +300,11 @@ class LDVImpl {
  VRMap virtRegToEqClass;

  /// Map user variable to eq class leader.
-  using UVMap = DenseMap<const MDNode *, UserValue *>;
+  using UVMap = DenseMap<const DILocalVariable *, UserValue *>;
  UVMap userVarMap;

  /// getUserValue - Find or create a UserValue.
-  UserValue *getUserValue(const MDNode *Var, const MDNode *Expr,
+  UserValue *getUserValue(const DILocalVariable *Var, const DIExpression *Expr,
                          bool IsIndirect, const DebugLoc &DL);

  /// lookupVirtReg - Find the EC leader for VirtReg or null.
@ -454,8 +457,9 @@ void UserValue::mapVirtRegs(LDVImpl *LDV) {
      LDV->mapVirtReg(locations[i].getReg(), this);
 }

-UserValue *LDVImpl::getUserValue(const MDNode *Var, const MDNode *Expr,
-                                 bool IsIndirect, const DebugLoc &DL) {
+UserValue *LDVImpl::getUserValue(const DILocalVariable *Var,
+                                 const DIExpression *Expr, bool IsIndirect,
+                                 const DebugLoc &DL) {
  UserValue *&Leader = userVarMap[Var];
  if (Leader) {
    UserValue *UV = Leader->getLeader();
@ -494,11 +498,11 @@ bool LDVImpl::handleDebugValue(MachineInstr &MI, SlotIndex Idx) {
  }

  // Get or create the UserValue for (variable,offset).
-  bool IsIndirect = MI.isIndirectDebugValue();
+  bool IsIndirect = MI.getOperand(1).isImm();
  if (IsIndirect)
    assert(MI.getOperand(1).getImm() == 0 && "DBG_VALUE with nonzero offset");
-  const MDNode *Var = MI.getDebugVariable();
-  const MDNode *Expr = MI.getDebugExpression();
+  const DILocalVariable *Var = MI.getDebugVariable();
+  const DIExpression *Expr = MI.getDebugExpression();
  //here.
  UserValue *UV = getUserValue(Var, Expr, IsIndirect, MI.getDebugLoc());
  UV->addDef(Idx, MI.getOperand(0));
@ -971,8 +975,10 @@ splitRegister(unsigned OldReg, ArrayRef<unsigned> NewRegs, LiveIntervals &LIS) {
    static_cast<LDVImpl*>(pImpl)->splitRegister(OldReg, NewRegs);
 }

-void
-UserValue::rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI) {
+void UserValue::rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI,
+                                 BitVector &SpilledLocations) {
+  SpilledLocations.resize(locations.size());
+
  // Iterate over locations in reverse makes it easier to handle coalescing.
  for (unsigned i = locations.size(); i ; --i) {
    unsigned LocNo = i-1;
@ -991,6 +997,7 @@ UserValue::rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI) {
    } else if (VRM.getStackSlot(VirtReg) != VirtRegMap::NO_STACK_SLOT) {
      // FIXME: Translate SubIdx to a stackslot offset.
      Loc = MachineOperand::CreateFI(VRM.getStackSlot(VirtReg));
+      SpilledLocations.set(LocNo);
    } else {
      Loc.setReg(0);
      Loc.setSubReg(0);
@ -1024,7 +1031,7 @@ findInsertLocation(MachineBasicBlock *MBB, SlotIndex Idx,
 }

 void UserValue::insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx,
-                                 unsigned LocNo,
+                                 unsigned LocNo, bool Spilled,
                                 LiveIntervals &LIS,
                                 const TargetInstrInfo &TII) {
  MachineBasicBlock::iterator I = findInsertLocation(MBB, Idx, LIS);
@ -1034,25 +1041,35 @@ void UserValue::insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx,
  assert(cast<DILocalVariable>(Variable)
             ->isValidLocationForIntrinsic(getDebugLoc()) &&
         "Expected inlined-at fields to agree");
-  if (Loc.isReg())
-    BuildMI(*MBB, I, getDebugLoc(), TII.get(TargetOpcode::DBG_VALUE),
-            IsIndirect, Loc.getReg(), Variable, Expression);
+
+  // If the location was spilled, the new DBG_VALUE will be indirect. If the
+  // original DBG_VALUE was indirect, we need to add DW_OP_deref to indicate
+  // that the original virtual register was a pointer.
+  bool NewIndirect = IsIndirect || Spilled;
+  const DIExpression *Expr = Expression;
+  if (Spilled && IsIndirect)
+    Expr = DIExpression::prepend(Expr, DIExpression::WithDeref);
+
+  MachineInstrBuilder MIB =
+      BuildMI(*MBB, I, getDebugLoc(), TII.get(TargetOpcode::DBG_VALUE))
+          .add(Loc);
+  if (NewIndirect)
+    MIB.addImm(0U);
  else
-    BuildMI(*MBB, I, getDebugLoc(), TII.get(TargetOpcode::DBG_VALUE))
-        .add(Loc)
-        .addImm(0U)
-        .addMetadata(Variable)
-        .addMetadata(Expression);
+    MIB.addReg(0U, RegState::Debug);
+  MIB.addMetadata(Variable).addMetadata(Expr);
 }

 void UserValue::emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS,
-                                const TargetInstrInfo &TII) {
+                                const TargetInstrInfo &TII,
+                                const BitVector &SpilledLocations) {
  MachineFunction::iterator MFEnd = VRM->getMachineFunction().end();

  for (LocMap::const_iterator I = locInts.begin(); I.valid();) {
    SlotIndex Start = I.start();
    SlotIndex Stop = I.stop();
    unsigned LocNo = I.value();
+    bool Spilled = LocNo != ~0U ? SpilledLocations.test(LocNo) : false;

    // If the interval start was trimmed to the lexical scope insert the
    // DBG_VALUE at the previous index (otherwise it appears after the
@ -1065,7 +1082,7 @@ void UserValue::emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS,
    SlotIndex MBBEnd = LIS.getMBBEndIdx(&*MBB);

    DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
-    insertDebugValue(&*MBB, Start, LocNo, LIS, TII);
+    insertDebugValue(&*MBB, Start, LocNo, Spilled, LIS, TII);
    // This interval may span multiple basic blocks.
    // Insert a DBG_VALUE into each one.
    while(Stop > MBBEnd) {
@ -1075,7 +1092,7 @@ void UserValue::emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS,
        break;
      MBBEnd = LIS.getMBBEndIdx(&*MBB);
      DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
-      insertDebugValue(&*MBB, Start, LocNo, LIS, TII);
+      insertDebugValue(&*MBB, Start, LocNo, Spilled, LIS, TII);
    }
    DEBUG(dbgs() << '\n');
    if (MBB == MFEnd)
@ -1090,10 +1107,11 @@ void LDVImpl::emitDebugValues(VirtRegMap *VRM) {
  if (!MF)
    return;
  const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo();
+  BitVector SpilledLocations;
  for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
    DEBUG(userValues[i]->print(dbgs(), TRI));
-    userValues[i]->rewriteLocations(*VRM, *TRI);
-    userValues[i]->emitDebugValues(VRM, *LIS, *TII);
+    userValues[i]->rewriteLocations(*VRM, *TRI, SpilledLocations);
+    userValues[i]->emitDebugValues(VRM, *LIS, *TII, SpilledLocations);
  }
  EmitDone = true;
 }
--- a/test/DebugInfo/X86/bbjoin.ll
+++ b/test/DebugInfo/X86/bbjoin.ll
@ -11,12 +11,12 @@
 ; }
 ; CHECK: ![[X:.*]] = !DILocalVariable(name: "x",
 ; CHECK: bb.0.entry:
-; CHECK:   DBG_VALUE 23, 0, ![[X]],
+; CHECK:   DBG_VALUE 23, debug-use _, ![[X]],
 ; CHECK:   DBG_VALUE %rsp, 0, ![[X]], !DIExpression(DW_OP_plus_uconst, 4, DW_OP_deref),
 ; CHECK: bb.1.if.then:
-; CHECK:   DBG_VALUE 43, 0, ![[X]],
+; CHECK:   DBG_VALUE 43, debug-use _, ![[X]],
 ; CHECK: bb.2.if.end:
-; CHECK-NOT:  DBG_VALUE 23, 0, ![[X]],
+; CHECK-NOT:  DBG_VALUE 23, debug-use _, ![[X]],
 ; CHECK:   RETQ %eax

 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
--- a/test/DebugInfo/X86/spill-indirect-nrvo.ll
+++ b/test/DebugInfo/X86/spill-indirect-nrvo.ll
@ -0,0 +1,103 @@
+; RUN: llc < %s | FileCheck %s
+; RUN: llc -O0 < %s | FileCheck %s
+
+; Make sure we insert DW_OP_deref when spilling indirect DBG_VALUE instructions.
+
+; C++ source:
+; #define FORCE_SPILL() \
+;   __asm volatile("" : : : \
+;                    "rax", "rbx", "rcx", "rdx", "rsi", "rdi", "rbp", "r8", \
+;                    "r9", "r10", "r11", "r12", "r13", "r14", "r15")
+; struct string {
+;   string();
+;   string(int i);
+;   ~string();
+;   int i = 0;
+; };
+; string get_string() {
+;   string result = 3;
+;   FORCE_SPILL();
+;   return result;
+; }
+
+; CHECK-LABEL: _Z10get_stringv:
+; CHECK: #DEBUG_VALUE: get_string:result <- [%RDI+0]
+; CHECK: movq   %rdi, [[OFFS:[0-9]+]](%rsp)          # 8-byte Spill
+; CHECK: #DEBUG_VALUE: get_string:result <- [DW_OP_plus_uconst [[OFFS]], DW_OP_deref] [%RSP+0]
+; CHECK: callq  _ZN6stringC1Ei
+; CHECK: #APP
+; CHECK: #NO_APP
+
+; ModuleID = 't.cpp'
+source_filename = "t.cpp"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64--linux"
+
+%struct.string = type { i32 }
+
+; Function Attrs: uwtable
+define void @_Z10get_stringv(%struct.string* noalias sret %agg.result) #0 !dbg !7 {
+entry:
+  %nrvo = alloca i1, align 1
+  store i1 false, i1* %nrvo, align 1, !dbg !24
+  call void @llvm.dbg.declare(metadata %struct.string* %agg.result, metadata !23, metadata !DIExpression()), !dbg !25
+  call void @_ZN6stringC1Ei(%struct.string* %agg.result, i32 3), !dbg !26
+  call void asm sideeffect "", "~{rax},~{rbx},~{rcx},~{rdx},~{rsi},~{rdi},~{rbp},~{r8},~{r9},~{r10},~{r11},~{r12},~{r13},~{r14},~{r15},~{dirflag},~{fpsr},~{flags}"() #3, !dbg !27, !srcloc !28
+  store i1 true, i1* %nrvo, align 1, !dbg !29
+  %nrvo.val = load i1, i1* %nrvo, align 1, !dbg !30
+  br i1 %nrvo.val, label %nrvo.skipdtor, label %nrvo.unused, !dbg !30
+
+nrvo.unused:                                      ; preds = %entry
+  call void @_ZN6stringD1Ev(%struct.string* %agg.result), !dbg !30
+  br label %nrvo.skipdtor, !dbg !30
+
+nrvo.skipdtor:                                    ; preds = %nrvo.unused, %entry
+  ret void, !dbg !30
+}
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+declare void @_ZN6stringC1Ei(%struct.string*, i32) unnamed_addr
+
+declare void @_ZN6stringD1Ev(%struct.string*) unnamed_addr
+
+attributes #0 = { uwtable }
+attributes #1 = { nounwind readnone speculatable }
+attributes #3 = { nounwind }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 6.0.0 ", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "t.cpp", directory: "C:\5Csrc\5Cllvm-project\5Cbuild")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 6.0.0 "}
+!7 = distinct !DISubprogram(name: "get_string", linkageName: "_Z10get_stringv", scope: !1, file: !1, line: 13, type: !8, isLocal: false, isDefinition: true, scopeLine: 13, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !22)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10}
+!10 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "string", file: !1, line: 7, size: 32, elements: !11, identifier: "_ZTS6string")
+!11 = !{!12, !14, !18, !21}
+!12 = !DIDerivedType(tag: DW_TAG_member, name: "i", scope: !10, file: !1, line: 11, baseType: !13, size: 32)
+!13 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!14 = !DISubprogram(name: "string", scope: !10, file: !1, line: 8, type: !15, isLocal: false, isDefinition: false, scopeLine: 8, flags: DIFlagPrototyped, isOptimized: true)
+!15 = !DISubroutineType(types: !16)
+!16 = !{null, !17}
+!17 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !10, size: 64, flags: DIFlagArtificial | DIFlagObjectPointer)
+!18 = !DISubprogram(name: "string", scope: !10, file: !1, line: 9, type: !19, isLocal: false, isDefinition: false, scopeLine: 9, flags: DIFlagPrototyped, isOptimized: true)
+!19 = !DISubroutineType(types: !20)
+!20 = !{null, !17, !13}
+!21 = !DISubprogram(name: "~string", scope: !10, file: !1, line: 10, type: !15, isLocal: false, isDefinition: false, scopeLine: 10, flags: DIFlagPrototyped, isOptimized: true)
+!22 = !{!23}
+!23 = !DILocalVariable(name: "result", scope: !7, file: !1, line: 14, type: !10)
+!24 = !DILocation(line: 14, column: 3, scope: !7)
+!25 = !DILocation(line: 14, column: 10, scope: !7)
+!26 = !DILocation(line: 14, column: 19, scope: !7)
+!27 = !DILocation(line: 15, column: 3, scope: !7)
+!28 = !{i32 -2147471175}
+!29 = !DILocation(line: 16, column: 3, scope: !7)
+!30 = !DILocation(line: 17, column: 1, scope: !7)
--- a/test/DebugInfo/X86/spill-nontrivial-param.ll
+++ b/test/DebugInfo/X86/spill-nontrivial-param.ll
@ -0,0 +1,89 @@
+; RUN: llc < %s | FileCheck %s
+
+; Make sure we insert DW_OP_deref when spilling indirect DBG_VALUE instructions.
+; In this example, 'nt' is passed by address because it is not trivially
+; copyable. When we spill the physical argument register at the barrier, we need
+; to insert DW_OP_deref.
+
+; #define FORCE_SPILL() \
+;   __asm volatile("" : : : \
+;                    "rax", "rbx", "rcx", "rdx", "rsi", "rdi", "rbp", "r8", \
+;                    "r9", "r10", "r11", "r12", "r13", "r14", "r15")
+; struct NonTrivial {
+;   NonTrivial();
+;   ~NonTrivial();
+;   int i;
+; };
+; int foo(NonTrivial nt) {
+;   FORCE_SPILL();
+;   return nt.i;
+; }
+
+; CHECK-LABEL: _Z3foo10NonTrivial:
+; CHECK: #DEBUG_VALUE: foo:nt <- [%RDI+0]
+; CHECK: movq    %rdi, -8(%rsp)          # 8-byte Spill
+; CHECK: #DEBUG_VALUE: foo:nt <- [DW_OP_constu 8, DW_OP_minus, DW_OP_deref] [%RSP+0]
+; CHECK: #APP
+; CHECK: #NO_APP
+; CHECK: movq    -8(%rsp), %rax          # 8-byte Reload
+; CHECK: movl    (%rax), %eax
+
+; ModuleID = 't.cpp'
+source_filename = "t.cpp"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64--linux"
+
+%struct.NonTrivial = type { i32 }
+
+; Function Attrs: nounwind uwtable
+define i32 @_Z3foo10NonTrivial(%struct.NonTrivial* nocapture readonly %nt) local_unnamed_addr #0 !dbg !7 {
+entry:
+  tail call void @llvm.dbg.declare(metadata %struct.NonTrivial* %nt, metadata !20, metadata !DIExpression()), !dbg !21
+  tail call void asm sideeffect "", "~{rax},~{rbx},~{rcx},~{rdx},~{rsi},~{rdi},~{rbp},~{r8},~{r9},~{r10},~{r11},~{r12},~{r13},~{r14},~{r15},~{dirflag},~{fpsr},~{flags}"() #2, !dbg !22, !srcloc !23
+  %i = getelementptr inbounds %struct.NonTrivial, %struct.NonTrivial* %nt, i64 0, i32 0, !dbg !24
+  %0 = load i32, i32* %i, align 4, !dbg !24, !tbaa !25
+  ret i32 %0, !dbg !30
+}
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+attributes #0 = { nounwind uwtable }
+attributes #1 = { nounwind readnone speculatable }
+attributes #2 = { nounwind }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 6.0.0 ", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "t.cpp", directory: "C:\5Csrc\5Cllvm-project\5Cbuild")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 6.0.0 "}
+!7 = distinct !DISubprogram(name: "foo", linkageName: "_Z3foo10NonTrivial", scope: !1, file: !1, line: 10, type: !8, isLocal: false, isDefinition: true, scopeLine: 10, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !19)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10, !11}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "NonTrivial", file: !1, line: 5, size: 32, elements: !12, identifier: "_ZTS10NonTrivial")
+!12 = !{!13, !14, !18}
+!13 = !DIDerivedType(tag: DW_TAG_member, name: "i", scope: !11, file: !1, line: 8, baseType: !10, size: 32)
+!14 = !DISubprogram(name: "NonTrivial", scope: !11, file: !1, line: 6, type: !15, isLocal: false, isDefinition: false, scopeLine: 6, flags: DIFlagPrototyped, isOptimized: true)
+!15 = !DISubroutineType(types: !16)
+!16 = !{null, !17}
+!17 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !11, size: 64, flags: DIFlagArtificial | DIFlagObjectPointer)
+!18 = !DISubprogram(name: "~NonTrivial", scope: !11, file: !1, line: 7, type: !15, isLocal: false, isDefinition: false, scopeLine: 7, flags: DIFlagPrototyped, isOptimized: true)
+!19 = !{!20}
+!20 = !DILocalVariable(name: "nt", arg: 1, scope: !7, file: !1, line: 10, type: !11)
+!21 = !DILocation(line: 10, column: 20, scope: !7)
+!22 = !DILocation(line: 11, column: 3, scope: !7)
+!23 = !{i32 -2147471481}
+!24 = !DILocation(line: 12, column: 13, scope: !7)
+!25 = !{!26, !27, i64 0}
+!26 = !{!"_ZTS10NonTrivial", !27, i64 0}
+!27 = !{!"int", !28, i64 0}
+!28 = !{!"omnipotent char", !29, i64 0}
+!29 = !{!"Simple C++ TBAA"}
+!30 = !DILocation(line: 12, column: 3, scope: !7)